Exhaust manifold bolt size

[chuckwp]

'37 Flathead V8. Are all the exhaust manifold bolt holes supposed to be 3/6"-16? The front holes on the one I am working on are messed up. They seem to be 7/16" partway and 3/8" the rest of the way, with the outer part being the 7/16" dimension. No sure what is going on here. I suspect someone has done something jiggy>

 

[chuckwp]

Never mind. I figured it out. They are 7/16"-14.

 

[Big hammer]

Wow I thought I was in the wrong forum, then I see you where.

 

[Flathead]

The front two holes are supposed to be 7/16, rest of holes are 3/8.